Human disturbances such as cars make elk act more vigilant than natural predators do, according to new research published in PLoS ONE.

That conclusion comes from a year-long study of elk over more than 5,000 square kilometers of private ranches, public land, and a national park in Alberta, Canada. The researchers observed elk herds and individual elk, recording how much time the animals spent eating, grooming, resting, fighting, walking and running, and vigilantly scanning their surroundings.

The team also noted factors that might affect the animals’ vigilance, including the distance to roads, the amount of traffic on each road, ruggedness of the terrain, and the likely locations of predators such as wolves and grizzly bears. Then the researchers tried to figure out which factors best explained their 1,294 observations of individual elk and elk herd behavior.

Roads with 12 or more cars per day seemed to play a bigger role than natural predators in determining how vigilant the elk acted, the team found. For example, herds less than 250 meters away from such roads were 23 percent more vigilant than herds more than 1,000 meters away. The more time elk spent scanning their environment, the less time they spent looking for food and eating.

The study shows that “the effects of humans in shaping behaviour of elk exceed those of habitat and natural predators,” the researchers write. They describe the area as “a true landscape of fear, where each human is perceived by elk to be a potential predator”. — Roberta Kwok | 30 November 2012

Source: Ciuti, S. et al. 2012. Effects of humans on behaviour of wildlife exceed those of natural predators in a landscape of fear. PLoS ONE doi: 10.1371/journal.pone.0050611.